Predictors of Complications during Percutaneous Multitrack Balloon Mitral Valvuloplasty

Background: Percutaneous mitral balloon valvuloplasty is the main procedure in mitral stenosis (MS). It can replace surgical commissurotomy in many cases; however, mitral regurgitation (MR) remains the major procedure complication. Objectives: This study was conducted to investigate predictors of MR as a complication followingpercutaneous mitral valvuloplasty (PMV) using multitrack balloon technique. Methods: This cohort study was conducted at both Menoufia University Hospital and Mabaret Misr Elkadima Hospital. We enrolled 121 patients with moderate to severe MS who were subjected to PMV using multitrack balloon technique during the period from October 2017 to October 2019. Transthoracic echocardiographic evaluation was performed for all patients before and after the procedure. Patients who developed severe MR post procedure were compared with other patients to identify important distinction points. Results: Most patients (N = 109, 90.1%) developed no/mild MR (group A), whereas 12 (9.9%) patients developed severe MR (group B) after PMV. Those who developed severe MR had significantly higher weight, height, body mass index, and body surface area (P value 35.8%, P - 13.289, P = 0.031) and MV commissural asymmetry of calcification (OR 67.48, CI 95% 5.759 - 790.72, P = 0.001) as significant predictors of outcomes of MV commissurotomy. Conclusion: Mitral valve calcification, balloon sizing, and MV asymmetry are significant factors that can predict the development of MR after balloon valvuloplasty.


Introduction
Mitral stenosis (MS) is characterized by a decrease in Mitral Valve (MV) orifice area leading to compromised left ventricular filling. The consequence is stagnation of blood proximal to the MV that results in elevated left atrial, pulmonary venous, and pulmonary artery pressure [1].
MS most often occurs decades after the occurrence of rheumatic fever. However, in developed countries, calcific changes of the mitral annulus cause Degenerative MS (DMS) in a sizeable proportion of patients, especially in the elderly [2].
Before the appearance of percutaneous therapy, the treatment of MS was dependable on and the range of techniques included open or closed commissurotomy and replacement with biological or mechanical prostheses. Later, the development of percutaneous devices allowed percutaneous balloon mitral valvuloplasty (PMV) to become, beginning in the 1980s, not only a valid alternative to surgery but also the procedure of choice for all MS patients with a favorable valve anatomy. Percutaneous balloon mitral valvuloplasty is a safe and cheap procedure, which does not require general anesthesia. It is not a contraindication for subsequent surgical valvuloplasty or valve replacement, and does not require permanent anticoagulant therapy, except for a few cases, such as atrial fibrillation, major dilation of the left atrium, or prior episodes of embolism [3].
Acute severe mitral regurgitation (MR) is the commonest complication which needs emergency surgery following a balloon mitral valvuloplasty (BMV). The structure of the mitral valve apparatus is a complex one and BMV can sustain injury to different components of the valve apparatus [4].
We aim in this study to trace the complication of mitral regurgitation during the procedure percutaneous balloon mitral valvuloplasty by using multitrack balloon.

Subjects and Methods
This interventional non-randomized cohort study was conducted on 121 patients who presented with moderate to severe MS and subjected to PMV using multitrack balloon technique in the period from October 2017 until October 2019. This study was conducted in cardiac catheterization laboratory in cardiology department in Menoufiya University hospitals. Local ethical committee approval was taken. Participating subjects were counseled, and written consents were taken as well.
The recruited patients were divided into 2 groups, according to resultant mitral regurgitation: Group A: included patients with no or mild mitral regurgitation and Group B: included patients with severe mitral regurgitation.
All cases presented with moderate to severe mitral stenosis, suitable mitral valve morphology, symmetric commissural morphology and both sexes were included. Exclusion criteria were presence of left atrial (LA) thrombi in transesophageal echocardiography, high echocardiography score, moderate to severe mitral regurgitation, and sever calcification of both commissures. The Multitrack balloon sizing was done by effective balloon dilatation area EBDA by using standard geometric formula [5].

Results
In Table 3

Discussion
Mitral Stenosis (MS) is almost invariably the result of chronic rheumatic heart disease secondary to one or more prior episodes of acute rheumatic fever. Since In otto et al. [6] introduced balloon valvuloplasty in 1984, this procedure has become the treatment of choice replacing surgical commissurotomy in many cases. Despite the high technical expertise in percutaneous mitral commissurotomy, mitral regurgitation remains a major procedure-related complication [7].
Actually PMC is an effective procedure for MS with any of its technique either by Inoue balloon (IB), metallic commissurotomy (PMMC), or Multi-Track Double Balloon (MTDB) as in the study of Sharieff et al. [8] where a total of 486 patients were subjected to PMV using any of the 3 techniques and the overall success rate was 97.3% for IB, 97.6% for PMMC, and 98.3% for MTDB. Overall, the transmitral gradient decreased from 20.7 ± 7.2 mmHg to 6.5 ± 3.7 mmHg (p<0.001) and Left atrial pressure decreased from 29.3 ± 8.4 mmHg to 16.1 ± 11.5 mmHg (p< 0.001) [8].
Also, in Egyptian study of Sherif et al. [9] mean pressure gradient dropped from 15.94 ± 5.46 mmHg to 5.85 ± 2.6 mmHg by different techniques of PMV and the Multi-Track system was able to induce largest increase in MV area [9].
Regarding Post-commissurotomy MR, 12 patients developed severe MR (9.9%) in the current study who were compared with other patients to identify important distinction points. Sever MR group showed significant higher weight, height, BMI and BSA (P value>0.001).
Higher incidence (13.3%) of severe MR was observed by Elsawy et al. [10] in his study since four of 30 patients who underwent multitrack PMV developed severe MR. However, in the study of Sadaka et al. [11] on 30 patients who underwent PBMV no one developed severe MR even after follow up of 3 months [11]. In addition, Hou et al [12] observed severe MR in 12 out of 1768 patients (0.68%) underwent PBMV.
In the current study there was no significant difference between the two studied groups regarding age or sex (P value=0.383, 0.394 respectively). In the same point of view, Elasfar and Elsokkary did not find significant difference between patients with post-Inoue PMV severe MR and other patients without severe MR regarding their age or sex [7].
Pre-operative RVSP in the current study was significantly higher among patients with severe MR (37.3 ± 2.0 for severe MR versus 35.0 ± 3.2, P value 0.002). This is in agreement with Farman et al, who showed that high RV pressure was correlated with unsuccessful procedures. They confirmed their results by multivariate logistic regression which showed that RV pressure is a significant predictive factor for a successful PTMC [13].
Regarding balloon sizing, it was significantly higher among patients who developed severe MR compared with patients with mild or no MR (P value 0.001).
Tastan et al. [14] studied 2 groups of patients undergoing PBMV. One group was allocated to conventional height-based balloon reference sizing (the HBRS group) and the other was allocated to balloons sized by the echocardiographic measurement of the diastolic inter-commissural diameter (the EBRS group). They noticed that the mean of the calculated balloon reference sizes was significantly higher in the HBRS than in the EBRS group and MR > 2+ was less in the EBRS group [14].
Finally, it is obvious that several factors can predict the development of severe MR after multi-track PMV as MV calcification, balloon sizing and MV asymmetry. It also must be noted that this study is the first one to concentrate on predictors of severe MR after multi-track PMV. However, the current study has some limitations that must be mentioned including absence the correlation with MV area and absence the comparison with outcomes of other techniques to detect the general role of procedure in developing MR.

Conclusion
Mitral valve calcification, balloon sizing and MV asymmetry are significant factors that can predict the development of severe mitral regurgitation after balloon valvuloplasty.
Recommendations a) Special attention should be paid to patients with higher BMI, MV calcification and MV asymmetry. b) Patients should be counseled about the risk of developing MR after the procedure and patients with higher BMI, MV calcification and MV asymmetry should know about their higher risk. c) Great attention should be conducted to choose a small balloon whenever possible.